path: root/doc
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authorBoris Kolpackov <boris@codesynthesis.com>2020-10-15 14:20:44 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2020-10-15 14:20:44 +0200
commit921c2d503a63f4769fdf1c7e6eb31be2706f9bea (patch)
tree487698c7e2877dec1eed4945cd2d1e9e09b7eb66 /doc
parent291a737de8f92a7f620853133aa404b98e552a21 (diff)
Add ability to specify fallback value for NULL substitutions with in.null
Diffstat (limited to 'doc')
1 files changed, 13 insertions, 0 deletions
diff --git a/doc/manual.cli b/doc/manual.cli
index 59084d6..0cd5a5e 100644
--- a/doc/manual.cli
+++ b/doc/manual.cli
@@ -8156,6 +8156,19 @@ target-specific variables. Typed variable values are converted to string
using the corresponding \c{builtin.string()} function overload before
+Using an undefined variable in a substitution is an error. Using a \c{null}
+value in a substitution is also an error unless the fallback value is
+specified with the \c{in.null} variable. For example:
+# buildfile
+h{config}: in{config}
+ in.null = '' # Substitute null values with empty string.
A number of other build system modules, for example, \l{#module-version
\c{version}} and \l{#module-bash \c{bash}}, are based on the \c{in} module and
provide extended functionality. The \c{in} preprocessing rule matches any